how to get the non english value of a DataTextField and its DataValueField from a dropdownlist in asp.net

Question

I have the following dropdownlist in my project which takes its data from its relevant SqlDataSource. The problem which I am facing with is that the dropdownlist includes non-english items(ProvinceName) and I can get neither the DataTextField value nor the DataValueField value of an item in code behind file.

here is the markup:

<div class="col-lg-6">
    <label for="ddlProvince" class="control-label">Province</label>
    <asp:DropDownList AutoPostBack="true" ID="ddlProvince" 
         DataSourceID="sqlDsProvince" DataTextField="ProvinceName" 
         DataValueField="ProvinceID" CssClass="dropdown form-control" runat="server" />
    <asp:SqlDataSource ID="sqlDsProvince" runat="server" ConnectionString="<%$ connectionStrings:connectionStr %>" SelectCommand="SELECT [ProvinceID], [ProvinceName] FROM [Provinces]" ProviderName="System.Data.SqlClient">
    </asp:SqlDataSource>
</div>

When I run the following statements

testLabel.Text = ddlProvince.SelectedItem.Text;

or

testLabel.Text=ddlProvince.SelectedValue;

I get the NullReferenceException

UPDATE I have another dropdownlist which doesn't include non-english item when I get items of this dropdownlist into testLabel everything works

<asp:DropDownList ID="ddlGraduationClass" CssClass="dropdown form-control" runat="server">
                                <asp:ListItem Text="12" Value="12"></asp:ListItem>
                                <asp:ListItem Text="14" Value="14"></asp:ListItem>
                            </asp:DropDownList>

Answer 1

The ddlProvince.SelectedItem & ddlProvince.SelectedValue has null value while the dropdownlist options doesn't have any option items during Page_Load event, or data rebinding during postback has occurred (considering AutoPostBack="true", so it can trigger postback). To rebind the data at first time, use IsPostBack check on corresponding event:

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        ddlProvince.DataSource = sqlDsProvince;
        ddlProvince.DataTextField = "ProvinceName";
        ddlProvince.DataValueField = "ProvinceID";
        ddlProvince.DataBind(); // don't forget to add this for binding dropdownlist items
    }
}

NB: ddlGraduationClass can also bound for another SqlDataSource in same ways like sample above.

References:

Why is my DropDownList's SelectedItem not working?

C# dropdown selected item null when list of strings/objects bound to the Data source